The ACE1 Electrical Impedance Tomography System for Thoracic Imaging

The design and performance of the active complex electrode (ACE1) electrical impedance tomography system for single-ended phasic voltage measurements are presented. The design of the hardware and calibration procedures allows for reconstruction of conductivity and permittivity images. Phase measurement is achieved with the ACE1 active electrode circuit which measures the amplitude and phase of the voltage and the applied current at the location at which current is injected into the body. An evaluation of the system performance under typical operating conditions includes details of demodulation and calibration and an in-depth look at insightful metrics, such as signal-to-noise ratio variations during a single current pattern. Static and dynamic images of conductivity and permittivity are presented from ACE1 data collected on tank phantoms and human subjects to illustrate the system’s utility.

[1]  Diederik Gommers,et al.  Lung monitoring at the bedside in mechanically ventilated patients , 2012, Current opinion in critical care.

[2]  David Isaacson,et al.  NOSER: An algorithm for solving the inverse conductivity problem , 1990, Int. J. Imaging Syst. Technol..

[3]  D. Isaacson,et al.  An implementation of the reconstruction algorithm of A Nachman for the 2D inverse conductivity problem , 2000 .

[4]  G.J. Saulnier,et al.  ACT3: a high-speed, high-precision electrical impedance tomograph , 1991, IEEE Transactions on Biomedical Engineering.

[5]  Ryan Halter,et al.  Design and implementation of a high frequency electrical impedance tomography system. , 2004, Physiological measurement.

[6]  B H Brown,et al.  A comparison of ventilatory and cardiac related changes in EIT images of normal human lungs and of lungs with pulmonary emboli. , 1994, Physiological measurement.

[7]  Matthias Kott,et al.  Dynamics of regional lung aeration determined by electrical impedance tomography in patients with acute respiratory distress syndrome , 2012, Multidisciplinary Respiratory Medicine.

[8]  A. Calderón,et al.  On an inverse boundary value problem , 2006 .

[9]  P Bertemes-Filho,et al.  A comparison of modified Howland circuits as current generators with current mirror type circuits. , 2000, Physiological measurement.

[10]  J C Newell,et al.  Reconstruction of conductivity changes due to ventilation and perfusion from EIT data collected on a rectangular electrode array. , 2001, Physiological measurement.

[11]  Raul Gonzalez Lima,et al.  Electrical impedance tomography , 2009, Current opinion in critical care.

[12]  D. Isaacson.  Distinguishability of Conductivities by Electric Current Computed Tomography , 1986, IEEE Transactions on Medical Imaging.

[13]  John G. Webster,et al.  Medical Instrumentation: Application and Design , 1997 .

[14]  O. Hoekstra,et al.  Ventilation and perfusion imaging by electrical impedance tomography: a comparison with radionuclide scanning. , 1998, Physiological measurement.

[15]  Jennifer L. Mueller,et al.  Real-Time Implementation of Calderón’s Method on Subject-Specific Domains , 2017, IEEE Transactions on Medical Imaging.

[16]  C. Dakin,et al.  Regional ventilation distribution in the first 6 months of life , 2010, European Respiratory Journal.

[17]  I Frerichs,et al.  Performance of electrical impedance tomography in detecting regional tidal volumes during one‐lung ventilation , 2008, Acta anaesthesiologica Scandinavica.

[18]  Christian Putensen,et al.  Electrical impedance tomography guided ventilation therapy , 2007, Current opinion in critical care.

[19]  Steffen Leonhardt,et al.  Assessment of regional lung recruitment and derecruitment during a PEEP trial based on electrical impedance tomography , 2008, Intensive Care Medicine.

[20]  Luca Konig,et al.  Design With Operational Amplifiers And Analog Integrated Circuits , 2016 .

[21]  Eung Je Woo,et al.  Multi-frequency EIT system with radially symmetric architecture: KHU Mark1 , 2007, Physiological measurement.

[22]  James Avery,et al.  A Versatile and Reproducible Multi-Frequency Electrical Impedance Tomography System , 2017, Sensors.

[23]  Samuli Siltanen,et al.  Linear and Nonlinear Inverse Problems with Practical Applications , 2012, Computational science and engineering.

[24]  D. Djajaputra.  Electrical Impedance Tomography: Methods, History and Applications , 2005 .

[25]  A. Nachman,et al.  Global uniqueness for a two-dimensional inverse boundary value problem , 1996 .

[26]  B. Rigaud,et al.  Experimental acquisition system for impedance tomography with active electrode approach , 2006, Medical and Biological Engineering and Computing.

[27]  Jennifer L. Mueller,et al.  Direct 2-D Reconstructions of Conductivity and Permittivity From EIT Data on a Human Chest , 2015, IEEE Transactions on Medical Imaging.

[28]  M. Cheney,et al.  Distinguishability in impedance imaging , 1992, IEEE Transactions on Biomedical Engineering.

[29]  K. Lowhagen,et al.  Regional intratidal gas distribution in acute lung injury and acute respiratory distress syndrome assessed by electric impedance tomography. , 2010, Minerva anestesiologica.

[30]  Andy Adler,et al.  Electrical impedance tomography system based on active electrodes , 2012, Physiological measurement.

[31]  R H Bayford,et al.  Design and performance of the UCLH mark 1b 64 channel electrical impedance tomography (EIT) system, optimized for imaging brain function. , 2002, Physiological measurement.

[32]  Melody Dodd,et al.  A Real-time D-bar Algorithm for 2-D Electrical Impedance Tomography Data. , 2014, Inverse problems and imaging.

[33]  R Bayford,et al.  Design and calibration of a compact multi-frequency EIT system for acute stroke imaging. , 2006, Physiological measurement.

[34]  R. G. Lima,et al.  Real-time detection of pneumothorax using electrical impedance tomography* , 2008, Critical care medicine.

[35]  Michael Capps,et al.  Evaluation of surrogate measures of pulmonary function derived from electrical impedance tomography data in children with cystic fibrosis , 2018, Physiological measurement.

[36]  R H Smallwood,et al.  Mk3.5: a modular, multi-frequency successor to the Mk3a EIS/EIT system. , 2001, Physiological measurement.

[37]  Andy Adler,et al.  Whither lung EIT: Where are we, where do we want to go and what do we need to get there? , 2012, Physiological measurement.

[38]  I Frerichs,et al.  Reproducibility of regional lung ventilation distribution determined by electrical impedance tomography during mechanical ventilation , 2007, Physiological measurement.

[39]  M. Cheney,et al.  Detection and imaging of electric conductivity and permittivity at low frequency , 1991, IEEE Transactions on Biomedical Engineering.

[40]  Gerhard Hellige,et al.  Detection of local lung air content by electrical impedance tomography compared with electron beam CT. , 2002, Journal of applied physiology.

[41]  Matti Lassas,et al.  REGULARIZED D-BAR METHOD FOR THE INVERSE CONDUCTIVITY PROBLEM , 2009 .

[42]  Pascal Olivier Gaggero,et al.  Miniaturization and distinguishability limits of electrical impedence tomography for biomedical application , 2011 .

[43]  Burkhard Lachmann,et al.  Regional pressure volume curves by electrical impedance tomography in a model of acute lung injury , 2000, Critical care medicine.

[44]  S J Hamilton,et al.  A direct D-bar reconstruction algorithm for recovering a complex conductivity in 2D , 2012, Inverse problems.

[45]  Keith D. Paulsen,et al.  A Broadband High-Frequency Electrical Impedance Tomography System for Breast Imaging , 2008, IEEE Transactions on Biomedical Engineering.

[46]  David Isaacson,et al.  Electrical Impedance Tomography , 2002, IEEE Trans. Medical Imaging.

[47]  David Isaacson,et al.  Reconstructions of chest phantoms by the D-bar method for electrical impedance tomography , 2004, IEEE Transactions on Medical Imaging.

[48]  Günter Hahn,et al.  Synchronous absolute EIT in three thoracic planes at different gravity levels , 2013 .

[49]  Ning Liu.  ACT4: A high-precision, multi-frequency electrical impedance tomograph , 2007 .

[50]  Harki Tanaka,et al.  Imbalances in regional lung ventilation: a validation study on electrical impedance tomography. , 2004, American journal of respiratory and critical care medicine.

[51]  Fernando Silva de Moura.  Nonlinear state estimation using the Unscented Kalman filter in electrical impedance tomography (Estimação não linear de estado através do unscented Kalman filter na tomografia por impedância elétrica) , 2013 .